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BOTANICAL CONTRIBUTIONS. 
1. Description of a new Stonecrop from [exico. 
By N. L. Britton. 
SEDUM MEXICANUM n. sp. 
He mene succulent, very brittle, the flowering stems 
weak, becoming 1 dm. long; leaves linear, sessile, com- 
pressed, tapering to a blunt tip, scattered on the flowering 
stems, more crowded on the sterile shoots, 8-20 mm. long, 
about 2 mm. wide; inflorescence of 3 usually 2-forked re- 
curving branches, 4~8 cm. long; flowers close together, 
sessile: bracts longer than the similar sepals; petals golden 
yellow, oblong , acute at the apex, — tapering into a 
short claw, widely spreading, 5-6 mm. lon g, 1.5 mm. wide, 
a little longer than the two outer sepals, twice as long as the 
style subulate, 1 mm. 
Grown from seeds sollegea by Mrs. Britton on a trap 
dyke near the City of Mexico, November, 1896. Flowered 
in cool house May, 1898. Very showy in bloom. (Type 
specimen in Herbarium of the New York Botanical Garden.) 
Cespitose Willows of Arctic America and the Rocky Mountains. 
By P. A. RYDBERG. 
The five summers spent by mein the Rocky Mountain re- 
gion have shown me how little was really known about the 
willows of that part of the country, and a collection of wil- 
lows from British America, which Mr. James Macoun sent 
me in 1897, persuaded me that we know still less about the 
arctic and subarctic species of North America. The reason 
is probably to be found at least partly in the fact that we have 
relied on a single man's knowledge of the genus Sa/v, and 
sent all our material to him for determination without trying 
individually to investigate it. The late Mr. Bebb, of Foun- 
taindale, Ill., was, I doubt not, well acquainted with the wil- 
